How to model coiled cable
Quickly use a screw modifier for the basic shape.



You could use a curve to make the second step easier - the extra objects addon will let you add a screwed curve.

Then just create the tail parts. I applied the screw modifier then I extruded but if you had used a path it would probably be easier



I copied and flipped the whole thing, using snapping to add it to the top of itself, thus making the top tail.



Then put the whole thing on a curve using a curve modifier.